Numerous variant embodiments of tools of this type are already known, with entirely manually-operated handling or with motor-driven assistance.
These tools have diverse shapes, in particular at the end that works the soil, as a function of the nature of the work to be performed and optionally of the nature of the soil and the plant cover.
As far as the manually-operated (non-motorized) tools are concerned:
U.S. Pat. No. 3,965,991 discloses a hoe equipped with an elongated handle, at the end of which is placed a cutting tool, with the ability to rotate around an axis perpendicular to said handle. The latter exhibits a sharpened blade along each of its major lengths, bent in the shape of a U, and inserted by its ends into the two free ends of a flattened tube, itself also bent in U-shape, the core of the latter being integral with the handle.
FR-A-2 394 971 discloses a hoe with a construction similar to the one described above. The cutting tool, itself also slightly mobile in rotation, consists of a blade bent in the shape of a U, but whose wings are bent at their end in a way that is parallel to the base of the U. It is at these two ends that the blade is then taken between two metal plates that are secured to the handle of the device.
Nevertheless, these hand-operated devices exhibit numerous drawbacks. The first is common to all hoeing or similar tools with manually-operated handling and consists in tedious handling and in quick tiring of the user. In addition, the latter is forced, particularly for ergonomic reasons, to change the tool as soon as he wants to change operations: uproot weeds, aerate the soil, break up clumps of earth, cut edges, etc. It is therefore necessary for him to carry entirely different tools.
So far as motor-driven or power-assisted tools are concerned:
U.S. Pat. No. 4,305,470 discloses an electric hoeing tool whose motor is located at the high end of the handle located opposite the cutting tool. The motor drives a shaft in rotation in the handle, which, thanks to two successive eccentric gears, creates a reciprocating rotational movement of the cutting tool. Nevertheless, by the nature of its mounting, the maintenance and eventual replacement of the blade are tedious and not very user-friendly operations. Moreover, the placement of the motor does not make it possible to use the weight of the latter advantageously, in particular to improve the penetration of the blade into the soil. Furthermore, no adjustment of the movement or of the position of the blade is provided.
FR-A-2 530 917 discloses an electric hoeing tool whose motor is located at the same end of the handle as the cutting tool (lower end), which makes it possible to take advantage of its weight. However, with this configuration, as with the one described in U.S. Pat. No. 4,305,470, the two-part cutting tool must be attached on both sides of the head, which necessitates access on both sides and thus creates a large number of possible openings for dust, speeding up the fouling of the motor, as well as moving parts or bearings susceptible to breaking. Moreover, stones are frequently found wedged between the two parts of the tool during use, forcing the work underway to stop.
These two known designs of motor-driven tools also share the major drawback of not making it possible to adjust, in relation to the handle, the middle position of the cutting tool in relation to which it performs its back-and-forth movement, while it has been found that this middle position is one of the essential parameters that determine the comfort of use and the effectiveness of the soil cultivation devices. Now, the gripping height of the device as well as the slope of the soil being worked prevent guaranteeing that this middle position is systematically ideal.
Furthermore, the document FR-A-2 546 706 discloses two different types of motor-driven soil cultivation devices that can be mounted on the same handle through which a drive shaft passes.
The first type of device (shown in FIGS. 1 to 4 of this document) comprises two tools in the shape of spades mounted on both sides of a transfer gear housing. These two spades are driven with elliptical movements that are 180° out of phase, by connecting rod/crank mechanisms and while being guided in translation in a bearing mounted articulated on a directional support arm.
Thus, this first type of device, besides a construction and a mechanism for transforming complex movements, comprises several out-of-phase tools driven with continuous rotational movements. Furthermore, the drive pin of the spades and their pivot pin are separate and offset.
The second type of device disclosed by the document FR-A-2 546 706 (shown in FIGS. 5 to 7) comprises several tools driven with a continuous rotational movement.
Finally, the document DE-A-10 2007 034 908 has as its object a motor-driven hoe or pick mounted on wheels. This device comprises a rotating motor driving a complex mechanism for transforming movement at two outputs, which displaces the tools that are attached at the end of slides in cyclical elliptical movements 180° out of phase.
Moreover, none of the tools of these two latter documents performs a hoeing work.